The emphasis of this proposal is to characterize a neonatal animal model of necroitizing enterocolitis (NEC) and to investigate the pathogenesis of this devastating disease of premature infants as it relates to PAF and other inflammatory mediators. Although intestinal injury in adult animals has been shown to be predominantly mediated by PAF, the etiology of neonatal NEC may be significantly different from adult bowel necrosis, and the importance of PAF in NEC in unknown. Neonatal NEC will be reproduced in newborn rats to simulate the human condition by exposing the animals to the known risk factors of NEC, i.e. formula feeding, hypoxia, and bacterial colonization. Subsequently, the roles of PAF and other mediators (endotoxin, endothelin, tumor necrosis factor, and thromboxane) will be evaluated in this model by 1) measuring plasma (all) and intestinal PAF, 2) studying PAF regulating enzyme expression and activity (using enzyme assays, Norther blot analysis, and in situ hybridization), 3) studying PAF receptor binding regulation and receptor gene transcription, and 4) inhibition of PAF and other mediators using specific inhibitors and monoclonal antibodies. In addition, endothelial cell monolayers will be used to evaluate interactions at the cellular level between hypoxia, PAF, and endothelin. Finally, premature human neonates will be studied to test the hypothesis that feeding stimulates endotoxin release, phospholipase A2 activation, PAF synthesis, and NEC. Results from these studies may suggest new therapeutic strategies for the prevention and treatment of neonatal NEC. The candidate is an academic neonatologist trained in the biochemical evaluation of PAF as it relates to neonatal pathophysiology. Application for the Clinical Investigator Award is designed to support protected time away from clinical concerns in order to solidify training in molecular biological techniques including Northern blot analysis and in situ hybridization. With the acquisition of these skills, this researcher will become competitive independently for extramural funding. Molecular biology training will be provided by the sponsor who is an established investigator; this training will take place at Children's Memorial Hospital where the sponsor maintains her laboratory. This award will enable the candidate to develop and skills necessary to accomplish these pursuits in my laboratory at Evanston Hospital.